1. Field of the Invention
The present invention relates to an image display device and a liquid crystal lens.
2. Description of the Related Art
Liquid crystal has fluidity like liquid, exhibits anisotropy in electrical and optical properties, and has a characteristic that its molecule alignment state can be variously controlled. Liquid crystal lenses having liquid crystal with such properties sealed between a pair of substrates and controlling a voltage to be applied to a liquid crystal layer to control a distribution characteristic of refractive index have been known. In JP 7-72445 A, JP 7-77748 A, and JP 2009-511942 T, image display devices including a liquid crystal lens on a viewer side (the side of a front surface or a display surface) are disclosed. For example, the image display device disclosed in JP 7-72445 A is a three-dimensional display device providing stereoscopic vision for a viewer.
FIGS. 7A and 7B explain a display principle of an image display device having a liquid crystal lens disposed at a front surface.
First in FIG. 7A, a voltage is not applied to a liquid crystal layer LC, so that the alignment of liquid crystal molecules is maintained in an initial alignment state. Therefore in FIG. 7A, the liquid crystal lens is in a state exhibiting no lens effect. In FIG. 7B, on the other hand, a voltage is applied to the liquid crystal lens, and the alignment state of liquid crystal molecules is changed by an electric field between first electrodes E1 and a second electrode E2, so that the liquid crystal lens is in a state exhibiting a lens effect.
In the case of FIG. 7B, transmitted lights from pixels of a display panel PNL are condensed by the liquid crystal lens, and travel in different directions from each other. Therefore, different images (for example, a two-dimensional image and a three-dimensional image) between the case of FIG. 7A and the case of FIG. 7B are provided for a viewer being at a predetermined position and viewing the image display device.